This application claims the priority of German Patent Document 199 54 475.1, filed Nov. 12, 1999, the disclosure of which is expressly incorporated by reference herein.
This invention relates to a process for balancing a shaft, particularly a cardan shaft with an attached oscillation damper. Processes are known in which the imbalances of rotors, also represented by rotating shafts, are eliminated by balancing. For balancing, the shaft is set in rotation on a balancing machine, and the size and position of the imbalance is indicated. Excess mass is removed at specific locations by boring, or weights are attached to the location opposite the imbalance to compensate.
A process for balancing two shafts attached to each other is described in German Patent Document DE 41 20 197 A1. The balancing of the unit as a whole is not hereby attempted. Instead, the radial runout of the first shaft, namely a transmission output shaft, is determined and compensating weight is determined by calculation, taking into account the relevant total rotor mass including all of the rotor masses attached to the shafts, and attached. The second shaft, a cardan shaft coupled with the transmission output shaft, can also be balanced separately. Any remaining residual imbalance of the cardan shaft is marked and both shafts are then assembled in such a way that the residual imbalance of the cardan shaft lies opposite the radial runout of the driven shaft.
When balancing a cardan shaft with an oscillation damper, the usual method of proceeding is to balance the cardan shaft as completely as possible, specifically with coupling and union elements mounted, but without the oscillation damper, and then attach appropriate mass compensation weights. Subsequently, the complete cardan shaft, including the oscillation damper and further coupling and union elements which are only mountable together with the oscillation damper, is balanced in three balancing planes, whereby mass is bored out of a damper ring of the oscillation damper in order to equalize the mass. The disadvantage of proceeding in this way is that two working cycles are required for balancing, which represents a large expense. It is further disadvantageous that, in order to complete the cardan shaft, additional necessary components for establishing the connection with a driveshaft are mounted on the oscillation damper, such as flexible disks and union elements of a coupling. The imbalance of these additional components is added to the damping ring of the oscillation damper, which does not produce an optimal damping function.
An oscillation damper as used for oscillation damping in the drivetrains of vehicles is, described in German Patent Document DE-AS 25 08 212, corresponding to U.S. Pat. No. 4,077,233 or DE-OS 25 34 684, corresponding to U.S. Pat. No. 4,114,472.
The invention specified in a first embodiment has as its basis the problem of minimizing production costs by reduction of processing time for balancing, as well as attaining an improvement of function and an increase of the service life of the oscillation damper.
This problem is solved by providing an attached oscillation damper including hub attached to the shaft, a damping ring lying concentric to the hub, and elastic elements elastically attached to both the hub and the damping ring, determining an imbalance of the assembly including the shaft and the oscillation damper in regard to size and relative position in at least one plane, measuring a radial runout of the damping ring in parallel to the assembly imbalance, calculating an imbalance of the damping ring corresponding to the radial runout taking geometrical and material data of the damping ring as a basis, determining an imbalance of the shaft without the damping ring by calculation of a difference between the imbalance of the assembly and the imbalance of the damping ring, and performing a mass compensation corresponding to position and size of the damping ring and the imbalance of the shaft on the shaft and the damping ring. The cycle time for balancing is shortened by determining the imbalance of the cardan shaft and the damping ring of the oscillation damper in one working cycle, whereby the imbalance of the entire system, including of the cardan shaft with add-on parts and oscillation damper, is determined in the usual way through balancing, and the imbalance of the damper ring is determined through concentricity measurement. The proportional imbalance of the cardan shaft with fixed masses attached to it is the difference between the imbalance of the entire system and the imbalance of the damping ring. The calculation operations required are undertaken for practical purposes by the balancing machine, which is equipped with the appropriate software. An improvement of the balancing quality thereby results in that the cardan shaft is assembled completely with all add-on parts and an exact separation of the imbalances resulting from the damping ring and those from the cardan shaft with add-on parts is thereby possible.
Thereby an improvement of the function of the damper naturally also results. In addition, its service life will be increased, as its elastic elements are stressed less due to the lower forces.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.